The present invention relates to the field of microwave thermal therapy of tissue. In particular, the present invention relates to a catheter for microwave thermal and cooling therapy of tissue adjacent a urethra to attain a selected width of at least a portion of the lower urinary tract during thermal therapy of prostatic tissue.
Many conduits are used in the human body to pass substances such as gases, fluids or solids from one organ to another organ, or out of the body. From time to time, some bodily conduits become restricted due to an obstruction, or restricted from another tissue impinging on the conduit. With such an obstruction or impingement, the conduit can lose its ability to pass fluids and/or other substances.
One example of a conduit that becomes restricted is the urethra, which is a portion of the lower urinary tract passing through the prostate. The prostate gland encircles the urethra immediately below the bladder. The prostate, which is the most frequently diseased of all internal organs, is the site of a common affliction among older men, benign prostatic hyperplasia (BPH), as well as a more serious affliction, cancer. BPH is a nonmalignant, bilateral nodular tumorous expansion of prostate tissue occurring mainly in the transition zone of the prostate. Left untreated, BPH causes obstruction of the urethra which usually results in increased urinary frequency, urgency, incontinence, nocturia and slow or interrupted urinary stream.
Recent treatment of BPH includes transurethral microwave thermal therapy in which microwave energy is employed to elevate the temperature of tissue surrounding the prostatic urethra above about 45.degree. C., thereby thermally damaging the tumorous prostate tissue. Despite recent successes in ablating such tumorous tissue by transurethral thermal therapy, further improvements can be made in this therapy to further maintain or enhance the patency of the lower urinary tract after the thermal therapy treatment. Maintaining or enhancing the patency of the lower urinary tract will improve functions such as urine flow which are not always improved with transurethral thermal therapy treatment (despite ablation of the tumorous tissue causing constriction of the urethra), and is accordingly highly desirable.